1. Field of the Invention
The present invention relates to an IP telephone system which achieves low power consumption of communication devices in the field of communication technology with the use of an IP (Internet Protocol) network.
1. Description of the Related Art
Conventionally, there are known technologies of communicating various types of sound data such as music, for example, BGM, peoples' voice, and the like, through the IP (Internet Protocol) networks such as the Internet and intranets. Japanese Patent Application Laid-Open Publication No. 2005-45737 discloses an example of communication technology of this type. Such a sound communication technology has been in practical use, in the form of communication devices (so-called IP telephones) with the use of VoIP (Voice over Internet Protocol), for example.
As one example of the above practical use, mutual communication between IP telephones (communication devices) will be described below. Analog sound data is digitally converted at a transmission source, and the digital data is frame-processed and divided into smaller units. Header information of a transmission destination is added for each of the divided sound data, whereby the sound data is transmitted (wirelessly communicated) in the form of divided smaller units referred to as RTP (Real-Time Transport Protocol) in sequential order to the destination through the IP network. After that, at the transmission destination, each of the received packets is restored to the original sound data, and the restored sound data is reproduced, whereby communication is conducted between the transmission source and the transmission destination.
In the sound communication technology using the IP telephones (communication devices), the IP network in which these IP telephones are connected to a wireless LAN is constructed, thereby achieving sound communication at comparatively low cost regardless of a distance or communication time between the transmission source and the transmission destination. This sound communication technology is available for use as a collaboration tool by combining the IP telephones with soft phones such as Skype or other fixed-line phones.
However, the current IP telephones (communication devices) entails a problem that they cannot be continuously used over a long time. This is because communication (telephone conversation) between the IP phones requires a process that consumes a large amount of power, thereby using up a battery capacity quickly. Here, in consideration of power consumption of the IP telephone, a large amount of battery power is consumed through each of processes of (1) digitizing the sound data, (2) restoring and reproducing the sound data from the packet forms, and (3) conducting wireless packet communication with the IP network, for example.
In view of the above-described circumference, it is an object of the present invention to provide an IP telephone system that enables communication devices to be continuously used over a long time by reducing power consumption.